Update on mosquito-borne diseases, chikungunya fever and dengue fever
The Centre for Health Protection (CHP) of the Department of Health (DH) today (November 21) reported the latest situation of chikungunya fever (CF) and dengue fever (DF).
Chikungunya fever
-----------------------
As of 5pm today,two new imported CF cases have been recorded.
The first case involves a 53-year-old female living in Kwai TsingDistrict. Initial investigation revealed that she visited Zhongshan in Guangdong between November 2 and 4. She developed joint pain and rash on November 19, followed by a fever yesterday (November 20). She sought medical attention at the Accident and Emergency Department of Princess Margaret Hospital on the same day.
The second case involves a 60-year-old female living in Kwai TsingDistrict. Initial investigation revealed that she visited Shenzhen in Guangdong on November 17. She developed joint pain on November 19, followed by rash on the following day (November 20). She sought medical attention at the Accident and Emergency Department of Yan Chai Hospital on the same day.
Both patients have been admitted for treatment in a mosquito-free environment. They are now in stable condition. Their blood sample tested positive for the chikungunya virus upon laboratory testing.
The 53-year-old patient has three household contacts, and five travel collaterals to Zhongshan, who are currently asymptomatic. The 60-year-old patient has two household contacts who travelled with her to Shenzhen. One of them developed mild joint pain. The CHP has referred the person concerned to the Accident and Emergency Department to undergo examination and blood test. All of the abovementioned individuals are under medical surveillance.
As both patients have travelled to CF-affected areasabout two weeks prior to symptom onset, the CHP preliminarilyconsidered that both cases were infected during their travel. These cases are classified as imported. The CHP will report the cases to the health authority of Guangdong Province. The CHP's epidemiological investigations are in progress.
Furthermore, in light of the local case involving a 68-year-old female who lives in Tung Hei Court in Shau Kei Wan, the CHP urged the residents living in the vicinity of the patient's residence to seek medical advice or contact the CHP immediately if they presented with a fever, rash or joint pain since October 15. The CHP collaborated with the Eastern District Services & Community Care Teams to distribute leaflets on CF prevention and questionnaire surveys to about 3 000 households in the affected areas in the vicinity of Tung Hei Court to remind residents to monitor for relevant symptoms and maintain good environmental hygiene at home.
As of 5pm today, the CHP has conducted assessments for over 4 950 individuals through the health consultation booth on 2/F, Hing Tung Shopping Centre in Shau Kei Wan, its inquiry hotline, questionnaire surveys and door-to-door visits at Tung Hei Court. No new symptomatic persons have been identified in the past six days. Four individuals with mild symptoms previously have been arranged to undergo blood tests, and all testednegative for the chikungunya virus.Since the health consultation booth has only sporadic visits recently and all individuals who underwent blood tests have returned negative results, the booth will cease operation starting tomorrow. The enquiry hotline (2125 2373) will continue to operate daily from 9am to 6pm.
Hong Kong has recorded a total of 67 confirmed CF cases this year. Among them, four were local cases, and the rest were imported cases.
Dengue fever
----------------
From November 14 to yesterday (November 20), the CHP recorded one imported DF case. The patient had travelled to India during the incubation period.
As of yesterday, 54 imported DF cases have been recorded so far this year. A total of 161 cases of DF were recorded in 2024, including 156 imported and five local cases.
According to the World Health Organization (WHO), the global incidence of DF has markedly increased over the past two decades, posing a substantial public health challenge. In 2024, the WHO recorded over 14 million cases, which was a record number. From January to July 2025, over four million cases and over 3 000 DF-related deaths have been reported in 97 countries/territories.
DF is prevalent in many neighbouring tourist destinations. Indonesia, India and Vietnam have each recorded over 90 000 cases so far this year; Malaysia and Thailand have each recorded over 40 000 cases; and Singapore has also recorded over 3 500 cases.Meanwhile, according to the Guangdong Provincial Center for Disease Control and Prevention, Guangdong Province has recorded 3 339 locally infected cases so far this year. A total of 130 cases were recorded in a week between November 3 and 9, with the highest number of cases recorded in Chaozhou, Shenzhen, Shantou, Guangzhou and Foshan.
Detailed information on the latest DF situation in Hong Kong, as well as neighbouring and overseas countries and areas, has been uploaded to the CHP'swebsite.
Continuously strengthening prevention and control
---------------------------------------------------------
TheFood and Environmental Hygiene Department (FEHD)and relevant departments have comprehensively enhanced the mosquito control operations in Hong Kong since July this year, and this has continued. Among these, the FEHD has conducted vector investigations and targeted mosquito control operations against the imported and local cases. In light of the local case, the FEHD has immediately conducted follow-up actions, including:
carrying out intensive fogging in scrubby areas within a 250-metre radius of the relevant locations to kill adult mosquitoes;
carrying out inspections of the locations, removing stagnant water, applying insecticides and disposing of abandoned water containers every week with a view to preventing mosquito breeding; and
enhancing public education efforts through organising health talks, setting up mobile education stations, and distributing publicity leaflets.
The abovementioned measures will be continued. Furthermore, the Government will further enhance the mosquito control efforts in addition to the existing measures.
Preventive measures taken by the public
----------------------------------------------
Members of the public should use DEET-containing insect repellents or other effective active ingredients properly to prevent mosquito bites, but the following precautions should be taken when using them:
read the label instructions carefully first;
apply right before entering an area with a risk of mosquito bites;
apply on exposed skin and clothing;
use DEET of up to 30 per cent for pregnant women and up to 10 per cent for children (For children who travel to countries or areas where mosquito-borne diseases are endemic or epidemic and where exposure is likely, those aged 2 months or above can use DEET-containing insect repellents with a DEET concentration of up to 30 per cent);
apply sunscreen first, then insect repellent;
reapply only when needed and follow the instructions; and
in addition to DEET, there are other insect repellents available on the market containing different active ingredients, such as IR3535 and picaridin. When using any insect repellent, the public should follow the usage instructions and precautions on the product label.
The FEHD also appeals to members of the public to continue to stay alert and work together to carry out mosquito prevention and control measures early, including inspecting their homes and surroundings to remove potential breeding grounds, changing water in vases and scrubbing their inner surfaces, removing water in saucers under potted plants at least once a week, and properly disposing of containers such as empty cans and lunch boxes. The FEHD also advises members of the public and property management agencies to keep drains free of blockage and level all defective ground surfaces to prevent the accumulation of water. They should also scrub all drains and surface sewers with an alkaline detergent at least once a week to remove any mosquito eggs.
The public should call 1823 in case of mosquito problems, and may visit the following pages for more information: the CF page of theCHPand theTravel Health Service, the latestTravel Health News,tips for using insect repellents, and the CHPFacebook Page,Instagram AccountandYouTube Channel, and also theMosquito Prevention and Control dedicated pageof the FEHD.
Source: AI-found images
FEHD releases fourth batch of gravidtrap indexes for Aedes albopictus in May
The Food and Environmental Hygiene Department (FEHD) today (May 21) released the fourth batch of gravidtrap indexes and density indexes for Aedes albopictus in May, covering 12 survey areas, as follows:
District |
Survey Area |
May 2026 |
First Phase Gravidtrap Index |
First Phase Density Index |
Eastern |
Shau Kei Wan and Sai Wan Ho |
9.1% |
1.4 |
Islands |
Tung Chung |
2.0% |
1.0 |
Kowloon City |
Hung Hom and To Kwa Wan |
6.7% |
1.5 |
Tai Po |
Tai Po East |
2.2% |
2.0 |
Tai Po West |
15.5% |
1.0 |
Tuen Mun |
Tuen Mun South |
9.1% |
1.4 |
District |
Survey Area |
May 2026 |
Area Gravidtrap Index |
Area Density Index |
Central and Western |
Kennedy Town and Shek Tong Tsui |
16.8% |
1.3 |
Eastern |
Chai Wan |
15.4% |
1.0 |
North Point and Quarry Bay |
18.9% |
1.4 |
Southern |
Aberdeen and Ap Lei Chau |
20.8% |
1.7 |
Sha Tin |
Sha Tin Town Centre and Fo Tan |
18.3% |
1.4 |
Tsuen Wan |
Tsuen Wan Town |
6.9% |
2.3 |
The fourth batch of gravidtrap indexes for Aedes albopictus in May includes First Phase Gravidtrap Indexes covering six survey areas and Area Gravidtrap Indexes covering six survey areas. Among which, six survey areas recorded gravidtrap indexes above 10 per cent, while Aberdeen and Ap Lei Chau in Southern District recorded a gravidtrap index above 20 per cent. Meanwhile, the gravidtrap indexes of six survey areas, namely Kennedy Town and Shek Tong Tsui in Central and Western District; North Point and Quarry Bay in Eastern District; Shau Kei Wan and Sai Wan Ho in Eastern District; Aberdeen and Ap Lei Chau in Southern District; Tai Po East in Tai Po District; and Tuen Mun South in Tuen Mun District, have recorded a decrease as compared to the indexes recorded in the last survey period, reflecting the progress of relevant mosquito control work.
With reference to the data from the past few years, the gravidtrap indexes start to rise from April or May every year. The actual timing and extent of the rise are affected by factors like weather conditions and rainfall. The average temperature and rainfall recorded in April this year were higher than those in the same period last year, creating favourable conditions for mosquito growth and breeding. As a result, the rise in gravidtrap indexes occurred earlier this year. With the increase in rainfall in May, the gravidtrap indexes are expected to rise further.
For survey areas which recorded indexes exceeding 10 per cent, in accordance with the mechanism implemented by the FEHD in response to the chikungunya fever (CF) situation (i.e. strengthening mosquito control work in areas with a gravidtrap index between 10 per cent and 20 per cent, instead of 20 per cent or above under the original mechanism), the FEHD is collaborating with relevant departments and stakeholders to identify locations with high mosquito infestations and carry out intensive and targeted mosquito control measures. The FEHD has initiated two prosecutions against the relevant construction site contractors following the discovery of mosquito breeding at construction sites in Tai Po District and Southern District. Moreover, following the discovery of stagnant water or stagnant water containers in a park, a construction site, a private housing estate, a clinic and a private premises in Tai Po District, Central and Western District, as well as Southern District, the FEHD has issued five statutory notices to the responsible persons-in-charge, requiring the clearance of such items within a specified timeframe. The FEHD, the relevant departments and stakeholders are following up on the mosquito control work, and will also organise exhibitions, distribute leaflets and posters, and notify residential estates that have subscribed to the gravidtrap Rapid Alert System, advising property management agents and residents to stay vigilant and work together in taking mosquito prevention and elimination measures. In addition, the FEHD will strengthen the monitoring of the gravidtrap index in the areas to review the effectiveness of the mosquito control work.
Public participation is crucial to the effective control of mosquito problems. The FEHD appeals to members of the public to continue to work together in strengthening personal mosquito control measures, including:
tidy up their premises and check for any accumulation of water inside the premises;
remove all unnecessary water collections and eliminate the sources;
check household items (those placed in outdoor and open areas in particular), such as refuse containers, vases, air conditioner drip trays, and laundry racks to prevent stagnant water;
change water in flower vases and scrub their inner surfaces thoroughly, and remove water in saucers under potted plants at least once a week;
properly cover all containers that hold water to prevent mosquitoes from accessing the water;
properly dispose of articles that can contain water, such as disposable meal boxes and empty cans; and
scrub drains and surface sewers with alkaline detergent at least once a week to remove any mosquito eggs.
Starting in August 2025, following the completion of the surveillance of individual survey areas, and once the latest gravidtrap index and the density index are available, the FEHD has been disseminating relevant information through press releases, its website and social media. It aims to allow members of the public to quickly grasp the mosquito infestation situation and strengthen mosquito control efforts, thereby reducing the risk of CF transmission.
Following recommendations from the World Health Organization and taking into account the local situation in Hong Kong, the FEHD sets up gravidtraps in districts where mosquito-borne diseases have been recorded in the past, as well as in densely populated places such as housing estates, hospitals and schools to monitor the breeding and distribution of Aedes albopictus mosquitoes, which can transmit CF and dengue fever. At present, the FEHD has set up gravidtraps in 62 survey areas of the community, with a surveillance period of two weeks. During the surveillance period, the FEHD will collect the gravidtraps once a week. After the first week of surveillance, the FEHD will immediately examine the glue boards inside the retrieved gravidtraps for the presence of adult Aedine mosquitoes to compile the Gravidtrap Index (First Phase) and Density Index (First Phase). At the end of the second week of surveillance, the FEHD will instantly check the glue boards for the presence of adult Aedine mosquitoes. Data from the two weeks of surveillance will be combined to obtain the Area Gravidtrap Index and the Area Density Index. The gravidtrap and density indexes for Aedes albopictus in different survey areas, as well as information on mosquito prevention and control measures, are available on the department's webpage (www.fehd.gov.hk/english/pestcontrol/dengue_fever/Dengue_Fever_Gravidtrap_Index_Update.html#).
FEHD releases fourth batch of gravidtrap indexes for Aedes albopictus in May Source: HKSAR Government Press Releases
FEHD releases fourth batch of gravidtrap indexes for Aedes albopictus in May Source: HKSAR Government Press Releases
FEHD releases fourth batch of gravidtrap indexes for Aedes albopictus in May Source: HKSAR Government Press Releases
FEHD releases fourth batch of gravidtrap indexes for Aedes albopictus in May Source: HKSAR Government Press Releases
FEHD releases fourth batch of gravidtrap indexes for Aedes albopictus in May Source: HKSAR Government Press Releases
